The present invention relates generally to flexible fluid-tight seals for pipe joints. More particularly, the present invention pertains to a cast-in-place gasket for use in various pipe joints. In one embodiment, the gasket can be used for sealing bell and spigot type pipe joints.
Sewer pipe assemblies are generally made of plastic, polyethylene, metal, concrete or other suitable materials. These materials are fabricated in many configurations and sizes to meet specific requirements and the preferences of users. In many such pipe assemblies, but certainly not all, grooves are formed or recesses are provided in the pipe to accommodate a gasket meant to seal between two pipes, such as a bell and a spigot. Usually the spigot, i.e., the male pipe, contains the groove. However, it is also possible that a formed groove in the bell, i.e., the female pipe, can be utilized. Some gaskets are integrally installed at the factory during fabrication of the sewer pipes, while others are simply applied at the job site.
In some known designs, especially if the pipe sections are made out of concrete, the gasket is simply mounted onto the pipe section, for example on a spigot, at the job site before the spigot and bell are connected. However, it would be beneficial to precast the gasket in place on the pipe during the time of manufacture of the pipe. This allows for a much easier installation in the field when the various pipe sections are connected to each other.
It is known to cast in place elastomeric bodies in openings of concrete manholes. Such bodies can be gaskets or washers for accommodating a sewer pipe which is inserted through the opening in the manhole. In such designs, the washers or gaskets are embedded in concrete about their outer margin. The elastomeric bodies lie normal to an axis of the pipe extending through a manhole opening. One problem with such gaskets is to positively and permanently anchor the gasket in the cementicious material which defines the inner surface of the manhole opening.
U.S. Pat. No. 6,089,618 discloses a sealing device for sealing an annular space between two pipes. The pipes can be made of a concrete material. One of the pipes forms a bell, including a socket with a substantially cylindrical inner surface. The other pipe is a spigot which can be introduced into the bell. A sealing device, including a sealing ring consisting of an elastic material, is mounted in the bell. An annular element, consisting of a non-elastic cellular plastic, is connected with the sealing ring. The sealing device is adapted to be positioned on the bell in a mold for molding the bell and for molding the sealing device into a socket of the bell at the cylindrical inner surface thereof. The annular element is positioned axially inside the sealing ring. However, this design necessitates the use of the annular element with the sealing ring.
Also known are embedded bell gaskets which require the use of a forming ring during the manufacture of the bell. An embedded bell gasket which does not require the use of installation forming rings during pipe manufacture would have a considerable economic advantage over systems which utilize a removable secondary element, or a permanently installed secondary element such as is disclosed in the U.S. Pat. No. 6,089,618.
Accordingly, it has been considered desirable to develop and a new and improved gasket and pipe joint design which would overcome the foregoing difficulties and others while providing a cast-in-place design for a gasket used in pipe joints made of a conventional pipe material.